چکیده انگلیسی

Abstract
This study tested differences in personality traits measured by the Multidimensional Personality Questionnaire (MPQ) in a community sample of adolescents with definite or probable conduct disorder (CD) diagnoses that did not progress to a diagnosis of antisocial personality disorder (ASPD) by early adulthood (n=43), those with definite or probable ASPD that persisted into early adulthood (n=68), or controls with neither a CD nor an ASPD diagnosis (n=716) to examine whether antisocial behaviour disorders that differed in course were associated with differences in personality traits. As expected, boys and girls with ASPD were significantly different from controls on constraint, and those with ASPD were significantly lower on constraint than those with only CD. The results suggest that individual differences in certain personality traits may contribute to differences in the type of antisocial behaviour disorder that emerges and thereby to the course of antisocial behaviour.

مقدمه انگلیسی

Introduction
Personality disorders affect around 11% of the general population (Ekselius, Tillfors, Furmark, & Fredrikson, 2001), making them among the most common mental disorders. Antisocial personality disorder (ASPD) is marked by antisocial behaviour that begins in childhood and persists into adulthood and affects about 4.5% of the population (Robins, Tipp, & Pryzbeck, 1991). The current conceptualization of personality disorders in the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV; American Psychiatric Association, 1994) requires that a maladaptive personality style be persistent with origins in adolescence or early adulthood. This conceptualization recognizes the consistency of personality and its foundations in adolescence. The DSM conceptualization of ASPD also raises the issue of the role of personality in the course of antisocial behaviour. Examination of various psychological dimensions, such as personality, that are associated with antisocial behaviour disorders will increase our understanding of these disorders.
One of the most widely used personality trait models, the big five or five factor model, has been used in research examining personality as it relates to antisocial behaviour in adolescents (e.g. John, Caspi, Robins, Moffitt, & Stouthamer-Loeber, 1994). Eyesenck's 3-factor model of personality has also been studied in relation to antisocial behaviour in adolescents (Saklofske & Eysenck, 1980) and was among the first of the trait models studied in this regard. More recently, Tellegen's 3-factor model of personality has been used in research on externalizing and antisocial behaviour (e.g. Krueger, McGue, & Iacono, 2001). The commonalities among personality trait models are notable, and preferences for the use of one model over another can surely be debated (Markon, Krueger, & Watson, 2005). The present study utilized a sample on which Tellegen's (2000) Multidimensional Personality Questionnaire (MPQ) was administered and, therefore, the focus of the literature review is on that measure.
The literature provides ample evidence of the association of personality traits like constraint (a broad measure of behavioural control, sensation seeking, and attitudes toward authority) and negative emotionality (a broad measure of affective reactivity and proneness to negative emotions) to antisocial behaviour in various forms. For example, Krueger, Schmutte, Caspi, Moffitt, Campbell et al. (1994) examined negative emotionality, constraint and other personality traits associated with delinquency in a sample of 862 18-year-old boys and girls using the MPQ. Various reports of antisocial behaviour (including official records) were correlated with scores from the MPQ. Low constraint and high negative emotionality were strongly associated with delinquency in both genders. This finding is consistent with other studies linking a similar personality profile to antisocial behaviour in boys (Taylor, Iacono, & McGue, 2000; Tremblay, Pihl, Vitaro, & Dobkin, 1994), to ASPD and psychopathy in men (Elkins, Iacono, Doyle, & McGue, 1997; Verona, Patrick, & Joiner, 2001), to general composites of externalizing behaviour in men and women (Krueger et al., 2001), and to conduct disorder (CD) and composites of antisocial behaviour in adolescent boys and girls (Moffitt, Caspi, Rutter, & Silva, 2001). Finally, a recent multivariate investigation of personality and externalizing disorders in children and adolescents showed that the pattern of high negative emotionality and low constraint was associated with CD, attention-deficit/hyperactivity disorder (ADHD), and the co-morbid CD-ADHD condition with the co-morbid disorder presentation being associated with a significantly more severe pattern than the single conditions ( Cukrowicz, Taylor, Schatschneider, & Iacono, 2006). Thus, there is little debate about the association of antisocial behaviour and constraint and negative emotionality.
What is less clear is whether personality traits are associated similarly with various antisocial behaviour disorders. The DSM diagnostic system includes CD (marked by fighting, lying, and various other antisocial behaviours diagnosed in children) and ASPD (which requires the presence of adult antisocial behaviours (AAB) in addition to evidence of CD). Most children with CD will not go on to evidence ASPD (Robins, 1966), and thus one of the differences between CD and ASPD is the persistence of the behaviour. Moffitt (1993) proposed that persistent and desistent antisocial behaviour is underlain by differences in cognitive functioning, biological factors, and social pressures. Personality traits may serve to organize behaviour toward antisocial versus prosocial trajectories, and some evidence suggests that boys who differ in their course of antisocial behaviour differ on personality dimensions.
Moffitt, Caspi, Dickson, Silva, and Stanton (1996) examined 11 primary MPQ personality traits at the age of 18 among boys designated as life-course-persistent (extreme antisocial behaviour in childhood and adolescence), adolescence-limited (extreme antisocial behaviour only in adolescence), abstainers (no extreme antisocial behaviour), and unclassified boys. They found that both life-course-persistent and adolescence-limited antisocial boys differed from abstainers on various primary MPQ scales that form constraint and negative emotionality. Antisocial boys showed lower traditionalism, lower control, higher aggression, and higher alienation than abstainers. The two delinquent groups differed significantly from each other on alienation (a negative emotionality scale) and on social potency and social closeness (two scales that contribute to the positive emotionality factor). Moffitt et al. (1996) found that the profile of MPQ scores was more extreme in the pathological direction (e.g. high aggression scale scores) among life-course-persistent boys than among adolescence-limited boys, suggesting that the course of antisocial behaviour may be linked to individual differences in personality. This work provided new insights into the relationship between personality traits and the course of antisocial behaviour, and suggested the need for further work.
Much of the previous research on personality and antisocial behaviour used cross-sectional data and operationalized antisocial behaviour in terms of delinquency, leaving unanswered questions about the extent to which personality traits differentially characterize psychological disorders defined by antisocial behaviour. Furthermore, there is limited research on gender effects on the associations between personality and antisocial behaviour. The present study aimed to extend the work of Moffitt, Caspi, Dickson, Silva, & Stanton (1996) and Moffitt, Caspi, Rutter, & Silva (2001) and others by examining the association of personality traits to DSM-defined antisocial behaviour disorders that differ in course (CD only vs. CD that progresses to ASPD by young adulthood) and to examine these associations in both boys and girls. In addition, the present study used longitudinal data to classify boys and girls into diagnostic groups, which provided a means to examine personality factors as they relate to differences in persistence and desistence of antisocial behaviour while also providing information about the relation of personality to diagnostic categories (CD and ASPD) common in both research and clinical settings. Based on previous findings regarding the associations between personality traits and antisocial behaviour, the following hypotheses were examined:
1.
Adolescents diagnosed with CD only or ASPD will be significantly higher on negative emotionality (and its associated subscales) and lower on constraint (and its associated subscales) than controls with neither diagnosis, reflecting the expectation that antisocial behaviour in general is associated with deviance in personality trait levels.
2.
Adolescents with ASPD will be significantly lower on constraint (and its associated subscales) and higher on negative emotionality (and its associated subscales) than adolescents with CD only, reflecting the expectation that the persistent antisocial behaviour disorder is underlain by more deviant personality trait levels than are non-persistent forms of antisocial behaviour disorder

نتیجه گیری انگلیسی

Results
Table 1 presents a summary of the group comparisons on each MPQ scale. Scores on a few individual scales were incomplete or missing resulting in slight variation in the df for analyses. The results partially supported the first hypothesis. Although the effect for group was significant for negative emotionality and constraint and for most of their subscales, controls did not differ significantly from boys and girls with CD only on any scale but aggression. As expected, the ASPD group differed significantly from the CD only group on constraint and its subscales providing support for our second hypothesis. However, those groups differed significantly only on the aggression subscale of negative emotionality.
Table 1.
Summary of Group Comparisons on Personality Scales
Scale F (df) p Control CD only ASPD
(n=716) (n=43) (n=68)
Mean (sd) Mean (sd) Mean (sd)
Constraint 34.38 (2, 802.78) .001 49.08a (8.95) 46.01a (8.63) 37.02b (10.11)
Control 23.70 (2, 794.47) .001 48.73a (9.37) 47.94a (8.66) 39.75b (9.74)
Harm avoidance 16.31 (2, 808.77) .001 48.71a (9.00) 46.04a (7.67) 39.84b (9.76)
Traditionalism 19.61 (2, 806.83) .001 50.15a (9.12) 48.49a (10.41) 41.17b (10.55)
Negative emotionality 7.06 (2, 794.29) .001 51.43a (8.97) 53.82a,b (8.68) 56.47b (8.30)
Stress reaction 1.54 (2, 806.57) .213 51.18 (9.52) 50.55 (9.65) 51.87 (8.12)
Alienation 5.74 (2, 802.51) .003 51.82a (8.94) 53.65a,b (7.86) 56.09b (8.10)
Aggression 26.92 (2, 800.12) .001 50.83a (8.86) 56.28b (8.28) 61.26c (9.08)
Positive emotionality 0.43 (2, 807.67) .651 51.08 (9.93) 49.85 (9.84) 51.18 (10.50)
Well-being 2.58 (2, 812.76) .076 50.74 (9.76) 48.42 (9.62) 48.41 (10.82)
Social potency 2.29 (2, 806.75) .101 50.65 (9.37) 52.32 (9.37) 54.06 (9.60)
Achievement 3.02 (2, 802.85) .049 49.52 (10.08) 47.13 (11.21) 49.15 (10.76)
Social closeness 0.21 (2, 791.62) .812 51.79 (9.59) 50.95 (10.94) 48.61 (10.24)
Note: Primary scales for each higher-order scale are listed under their higher-order scale and are denoted by an indent. Bold type indicates that the F-test for the scale was significant at the corrected p-value (.017 for higher-order scales; .005 for primary scales). Differences are reported only for comparisons made following a significant F-test at the corrected p-value; means in the same row that do not share a subscript differ at p<.05 in the least significant difference comparison.
Table options
The group × gender interaction was not significant for any of the MPQ scales, indicating no statistical difference in the pattern of findings across gender within groups. To confirm this, analyses were conducted separately by gender and all group differences were the same across gender with one exception: controls and CD only boys did not differ significantly on the aggression scale. The main effect for gender (tested in the models examining the full sample) was significant (p<.001) for two scales: social closeness (boys scored lower than girls) and aggression (boys scored higher than girls).
Discussion
Previous research has linked certain personality traits to antisocial behaviours in men, women, and children. Thus, personality traits may serve as part of the underlying psychological structure for the development of certain psychological disorders, including those related to antisocial behaviour. Though previous research has examined personality traits in adolescents with CD and other associated conditions (e.g. ADHD), there are no published reports on the personality traits associated with DSM-defined antisocial behaviour disorders (CD and ASPD) in the same sample. Given the practical clinical relevance of the DSM in identifying antisocial youth, it is important to investigate correlates of antisocial behaviour defined by DSM diagnostic categories. The present study examined whether various personality traits were associated with antisocial behaviour disorders in adolescents that differed in their progression in order to provide additional insights into factors that might relate to the development and course of antisocial behaviour.
Our results partially supported our first hypothesis in that adolescent boys and girls with ASPD were significantly different from controls on constraint and each of its subscales and on negative emotionality and two of its subscales (alienation and aggression). However, adolescents with CD only were not different from controls on most scales. These results suggest that adolescents who have CD that does not develop into ASPD are different in their personality from non-antisocial adolescents only with regard to dimensions related to aggression, and not with regard to personality dimensions related to negative affectivity. Our second hypothesis was supported in that adolescent boys and girls with ASPD were significantly lower on constraint and all of its subscales than adolescents with a CD only diagnosis. However, contrary to expectation, those groups differed significantly only on the aggression subscale of negative emotionality. These results suggest that personality traits related to behavioural control, thrill-seeking, and traditional values may be related to which form of disorder manifests: a more persistent personality disorder (ASPD) or a non-persistent period of antisociality (CD). Finally, our exploration of gender differences showed that boys and girls across groups had similar personality patterns, suggesting that personality traits are associated with antisocial behaviour disorders in a similar manner across gender.
The present findings extended the work of Moffitt, Caspi, Dickson, Silva, & Stanton (1996) and Moffitt, Caspi, Rutter, & Silva (2001) and others to clinically defined groups of persistent and desistent antisocial adolescents. The present results also extended Moffitt et al. (2001) work with boys and girls and provided support for the notion that antisocial behaviour disorders are associated with similar personality traits in boys and girls. Furthermore, the present study extended earlier findings from the MTFS sample (e.g. Iacono et al., 1999) and other samples (e.g. Ge & Conger, 1999; Krueger, 1999; Krueger et al., 1994) by demonstrating a greater deviance in personality features among adolescent boys and girls with ASPD as compared to adolescents with only CD on the constraint personality dimension. Our results were not as consistent with previous findings with regard to negative emotionality. The aggression subscale did show differences across antisocial behaviour disorder groups as had been found previously, but the negative emotionality higher-order factor showed a significant difference only between the ASPD group and controls. This inconsistency may reflect differences in the definition used for antisocial behaviour and methodology in that a previous investigation found a significant overall correlation between antisocial behaviour and negative emotionality (Krueger et al., 1994), whereas we examined differences in negative emotionality between two diagnostic groups of antisocial youth. Furthermore, the aggression subscale taps a personality dimension with ties in content to the behavioural disorders used to define groups in this study and, therefore, our findings with regard to that scale are not surprising, although they are consistent with the findings of Moffitt et al. (1996) in which life-course-persistent delinquents had high aggression scores than adolescence-limited delinquents.
In sum, the present results provided some support for the idea that personality may serve to organize behaviour that leads to a more persistent antisocial behaviour trajectory for some (i.e. those with more extreme levels of constraint) and a desistent antisocial behaviour trajectory for others (i.e. those with less extreme levels of constraint). Our careful assignment of participants to diagnostic groups allowed us to compare an apparently desistent antisocial group (CD only) whose antisocial behaviour was limited to childhood/adolescence to a group with a continuous course of antisocial behaviour (ASPD group) and our results suggest that adolescents with CD only are not only descriptively different but may also be aetiologically distinct from those with ASPD. Given that the control and CD only groups did not differ significantly on most personality traits, it seems unlikely that personality traits contribute substantially to the aetiology of CD when it is not persistent but rather confined to adolescence. Instead, other factors such as peer influences (e.g. antisocial friends, rejection by peers) might be a relatively more important influence on the development of non-persistent CD than underlying, genetically influenced personality traits. In contrast, the aetiology of ASPD may indeed include extreme personality traits such as aggression, lack of adherence to traditional values, and sensation-seeking, and the stability of those traits may in part underlie the stability or continuity in the antisocial behaviour of those with ASPD.
The major strengths of this study included the use of (a) a large epidemiological sample, (b) structured clinical interviews for measuring CD and ASPD, (c) a personality measure that has been widely used in research on antisocial behaviour, (d) longitudinal data to define groups that afforded a comparison of CD cases that do not develop into ASPD to cases of CD that do make such a progression to cases of late-onset AAB without a preceding CD diagnosis, and (e) girls in the sample to allow for a comparison cross gender. Although some might argue that the use of twins and not singletons was a limitation of the present study, recent research has demonstrated the comparability of MPQ personality trait variances from twin and singleton samples, indicating that twins are representative of the general population with regard to personality (Johnson, Krueger, Bouchard, & McGue, 2002). The use of a predominantly white sample was a limitation of the present study and results might not generalize to non-white populations.
The nature of the antisocial behaviour disorders makes them particularly problematic for society, especially in the case of ASPD, which has a persistent course. The present study suggests that individual differences in certain personality traits may be related to the type of antisocial behaviour disorder that develops, and this link is present by adolescence. This finding may have implications for interventions aimed at identifying youth who are at high risk for persistent antisocial behaviour problems. Indeed, personality assessment is inexpensive and non-invasive and could help improve efforts at predicting which children with CD will progress to an ASPD diagnosis. Future studies should examine the contribution of personality traits to the development of CD and ASPD to shed light on the extent to which personality shapes the trajectory of antisocial behaviour and the potential effects that antisocial behaviour problems have on the shape of personality.